Method of treating slag.



S.B.LADD. METHOD OF TREATING SLAG.

APPLICATION FILED JUNE 2, 1906.

Patented July 27, 1909.

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Wtfneases UNITED STATES PATENT OFFICE.

STORY B. LADD, OF WASHINGTON, DISTRIC-TOF COLUMBIA.

METHOD OF TREATING SLAG.

Specification of Letters Patent.

Patented July 27, 1909.

Application filed June 2, 1996. Serial No. 319,875.

To all wnom it may concern:

Be it known that 1, STORY B. LADD, a

citizen of the United States, residing at lVashington, in the District of Columbia, have invented certain new and useful Improvements" in Methods of Treating Slag, of which the following is a specification. I

This invention is a method of treating slag for the purpose of recovering therefrom mechanicallysuspended or retained metals or metal-bearing compounds.

The method is more particularly applicable to the separation and recovery of copper or copper matte from slags produced in the usual operation of copper smelting. Such slags'usually carry from 0.3 to 0.5 per cent, or even more, by weight, of copper which cannot be effectively separated there- 'from by simple settling, either because the sidence is complete or has proceeded as far as commercially practicable. In practice the operation is preferably continuous, the slag and matte being tapped from the smelting furnace into a settling vessel providedwith means for imparting heat to the slag and means for withdrawing the separated matte or metal. The treated slag is permitted to overflow from the settling vessel at a rate proportionate to the rate at which it is supplied thereto.

For a full understanding of the invention reference is made to the accompanying draw ings showing one -form of apparatus for carrying the same into effect.

Figure 1 is a plan view, partly in horizontal section, of a settling vessel, provided with electrical heating means; and Fig. 2 is a vertical section on line 22 of Fig. 1.

1 represents a tank or settling vessel, preferably cylindrical and comparatively shallow. The vessel shown comprises a sheetsteel body 2 interiorly lined with refractory brick- 3. An inlet 4 for the slag and matte and an outlet 5-for the treated slag are pro vided, preferably at diametrically opposite points at the normal slag level.

6 represents atap for matte.

' Oppositely disposed electrodes 7, 8 are provided intermediate the inlet and outlet, and somewhat below the normal sla level in order that the heat may be applled beneath the surface of the body of slag and that the current .ma not be interrupted when matte is tapped om the settl' "vessel. These electrodes preferably consist 0 blocks of carbon or graphite, supported a by the lining 3 of thesettling vessel and protected by a lilting 9 of clay or other suitable material.

Electrica'l connection is established through rods 10 of metal or of graphite screwedor otherwise secured to the blocks 7 ,8 and extending through the walls of the tank and insulated therefrom. .A double advantage is secured by applying the heat beneath the surface of the body o f slag as above described: First, the surface remains comparatively cool and may even crust over except in immediate proximity to the inlet, thereby so preventing serious loss of heat by radiation and rendering it practicable 'to effectively separate the meal or matte in uncovered vessels; SQGOHQ, this mode of application of the heat iiisures-nn even fluidity throughout the main "body of slag, whereas an application-of heat from the surfacemay render the upper portion of the slag rel'ativelyfluid,

while the lower portion remains too viscous for effectively settling. In such casirmatte separated from the upper portion of the slag is merely concentrated in the lower por-- tion, and is not recovered. v

In operation the slag and matte are. admitted at 4 to the settling vessel 1, and a separation occurs therein, the matte collect ing beneath the slag and being withdrawn at intervals through the tap 6,. and the slag being permitted to overflow at 5. Either a direct or alternatingocurrent maybecaused to traverse the sla between the electrodes -7, 8, the volume 0 current being sufficient to maintain the slag in acompa-ratively fluid condition and to facilitate the separation of the values therefrom. The rate of subgeneral proportionate to the fluidity of the slag and to its temperature, and for this reason I prefer to superheat the slag, that is to say, to impart to it suflicient heat to maintain it at a higher temperature than that at "which it isreceived from the smelting fur- Y sidence of the metal-bearing particles is in nace. By so superheating the slag a commercially suflicient separationof the values may be secured in apparatus of smaller capacity than would otherwise be required.

I do not limit myself to the use ofheating means substantially as shown, for it will be understood that these may be variously modified; for instance, the heat may be applied to the slag by means of a resister traversing the same or in proximity thereto. The heat of the settling vessel may be economized by checking radiationtherefrom by known means, as by the use of a suitable cover and of appropriate coverings for the radiating surfaces; or the heating current may be so applied as to permit the formation of a heat-retaining crust upon the exposed surface of the slag.

I claim 1. The method of treating slag to separate Values therefrom which conslsts in applying heat beneath the surface of abody of slag and thereby maintaining it in a fluid condition for such time as is required to effect a substantially complete subsidence of the metallic-values, substantially as described.

2. The method of treating slag to separate values therefrom which consists in transmitting an electric current through a body of slag and thereby maintaining said body in a fluid condition for such time as is required to effect a substantially complete subsidence of the metallic values, substantially as described.

3. The method of treating slag to separate values therefrom which conslsts in applying heat beneath the surface of a flowing body of slag and thereby maintaining it in a fiuid condition for such time as is required to effect a substantially complete subsidence of the metallic values, substantially as described.

4. The method of treating slag to separate values therefrom which consists in transmittin an electric current through a flowing b0 y of slag in a direction transverse to its line of flow and thereby maintaining it in a fluid condition for such time as is required to effect a substantially complete subsidence of the metallic values, substantially as described.

5. The method of treating slag to separate values therefrom which consists in transmitting an electric current through a flowing bodyof slag in a direction transverse to its line of flow, thereby superheating the slag,

and permitting the metallic values to*subside, substantially as described.

In testlmony whereof, I affix my signature in presence of two witnesses.

. STURY B. LADD. lVitnesses:

, EUGENE A. BYRNEs,

A. F. "Tnsnn rrs. 

